Seasonal Change in Titan's Cloud Activity


Understanding the seasonal evolution of Titan's clouds, and of any precipitation associated with them, is essential for interpreting the geological observations of fluid flow features observed over a wide range of Titan latitudes with the Cassini/Huygens spacecraft. Ground-based images of Titan over the past five years have shown evidence of frequent storm and cloud activity near the south pole, but never anywhere close to the latitude of the Huygens landing site. While the presence of Titan’s methane meteorological cycle is now well established, a fundamental understanding of the seasonal dynamics of Titan’s clouds remains elusive. Over the past year, we have observed a breakup of the south polar cloud system and cloud activity moving northward. Observations over the next few years as Titan moves toward equinox will be critical for testing competing cloud formation hypotheses. While infrequent observations from Cassini flybys are vital for studying the morphologies of clouds and occasional cloud outbursts, only ground-based nightly monitoring can provide the type of dataset necessary to determine the frequency, duration, and altitudes of large cloud outbursts and the nominal daily cloud systems. I will discuss the results of our new nightly Titan monitoring program with the NASA Infrared Telescope Facility as well as results from our latest adaptive optics observations with Keck and Gemini. These datasets will enable us to determine the timescales of both small and large cloud formation/dissipation and place the Cassini observations in the broader context of the full range of cloud activity on Titan.